1 //
2 // Copyright 2014 The ANGLE Project Authors. All rights reserved.
3 // Use of this source code is governed by a BSD-style license that can be
4 // found in the LICENSE file.
5 //
6
7 // Based on Simple_VertexShader.c from
8 // Book: OpenGL(R) ES 2.0 Programming Guide
9 // Authors: Aaftab Munshi, Dan Ginsburg, Dave Shreiner
10 // ISBN-10: 0321502795
11 // ISBN-13: 9780321502797
12 // Publisher: Addison-Wesley Professional
13 // URLs: http://safari.informit.com/9780321563835
14 // http://www.opengles-book.com
15
16 #include "SampleApplication.h"
17
18 #include "texture_utils.h"
19 #include "util/Matrix.h"
20 #include "util/geometry_utils.h"
21 #include "util/shader_utils.h"
22
23 #include <cmath>
24
25 class SimpleVertexShaderSample : public SampleApplication
26 {
27 public:
SimpleVertexShaderSample(int argc,char ** argv)28 SimpleVertexShaderSample(int argc, char **argv)
29 : SampleApplication("SimpleVertexShader", argc, argv)
30 {}
31
initialize()32 bool initialize() override
33 {
34 constexpr char kVS[] = R"(uniform mat4 u_mvpMatrix;
35 attribute vec4 a_position;
36 attribute vec2 a_texcoord;
37 varying vec2 v_texcoord;
38 void main()
39 {
40 gl_Position = u_mvpMatrix * a_position;
41 v_texcoord = a_texcoord;
42 })";
43
44 constexpr char kFS[] = R"(precision mediump float;
45 varying vec2 v_texcoord;
46 void main()
47 {
48 gl_FragColor = vec4(v_texcoord.x, v_texcoord.y, 1.0, 1.0);
49 })";
50
51 mProgram = CompileProgram(kVS, kFS);
52 if (!mProgram)
53 {
54 return false;
55 }
56
57 // Get the attribute locations
58 mPositionLoc = glGetAttribLocation(mProgram, "a_position");
59 mTexcoordLoc = glGetAttribLocation(mProgram, "a_texcoord");
60
61 // Get the uniform locations
62 mMVPMatrixLoc = glGetUniformLocation(mProgram, "u_mvpMatrix");
63
64 // Generate the geometry data
65 GenerateCubeGeometry(0.5f, &mCube);
66
67 // Set an initial rotation
68 mRotation = 45.0f;
69
70 glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
71 glCullFace(GL_BACK);
72 glEnable(GL_CULL_FACE);
73
74 return true;
75 }
76
destroy()77 void destroy() override { glDeleteProgram(mProgram); }
78
step(float dt,double totalTime)79 void step(float dt, double totalTime) override
80 {
81 mRotation = fmod(mRotation + (dt * 40.0f), 360.0f);
82
83 Matrix4 perspectiveMatrix = Matrix4::perspective(
84 60.0f, float(getWindow()->getWidth()) / getWindow()->getHeight(), 1.0f, 20.0f);
85
86 Matrix4 modelMatrix = Matrix4::translate(angle::Vector3(0.0f, 0.0f, -2.0f)) *
87 Matrix4::rotate(mRotation, angle::Vector3(1.0f, 0.0f, 1.0f));
88
89 Matrix4 viewMatrix = Matrix4::identity();
90
91 Matrix4 mvpMatrix = perspectiveMatrix * viewMatrix * modelMatrix;
92
93 // Load the matrices
94 glUniformMatrix4fv(mMVPMatrixLoc, 1, GL_FALSE, mvpMatrix.data);
95 }
96
draw()97 void draw() override
98 {
99 // Set the viewport
100 glViewport(0, 0, getWindow()->getWidth(), getWindow()->getHeight());
101
102 // Clear the color buffer
103 glClear(GL_COLOR_BUFFER_BIT);
104
105 // Use the program object
106 glUseProgram(mProgram);
107
108 // Load the vertex position
109 glVertexAttribPointer(mPositionLoc, 3, GL_FLOAT, GL_FALSE, 0, mCube.positions.data());
110 glEnableVertexAttribArray(mPositionLoc);
111
112 // Load the texcoord data
113 glVertexAttribPointer(mTexcoordLoc, 2, GL_FLOAT, GL_FALSE, 0, mCube.texcoords.data());
114 glEnableVertexAttribArray(mTexcoordLoc);
115
116 // Draw the cube
117 glDrawElements(GL_TRIANGLES, static_cast<GLsizei>(mCube.indices.size()), GL_UNSIGNED_SHORT,
118 mCube.indices.data());
119 }
120
121 private:
122 // Handle to a program object
123 GLuint mProgram;
124
125 // Attribute locations
126 GLint mPositionLoc;
127 GLint mTexcoordLoc;
128
129 // Uniform locations
130 GLuint mMVPMatrixLoc;
131
132 // Current rotation
133 float mRotation;
134
135 // Geometry data
136 CubeGeometry mCube;
137 };
138
main(int argc,char ** argv)139 int main(int argc, char **argv)
140 {
141 SimpleVertexShaderSample app(argc, argv);
142 return app.run();
143 }
144